A wireless power transfer system includes a power transmission coil device and a power reception coil device, and implements wireless power transmission using electromagnetic induction, magnetic resonance, etc. between coils. For example, the wireless power transfer system is applied to a power feeding system of an electric vehicle or a plug-in hybrid vehicle. In this case, the power reception coil device is installed in a vehicle.
It has been known to dispose a conductive plate, etc. on a rear surface of the power reception coil device (that is, an opposite surface to a surface opposing the power transmission coil device, between the power reception coil device and the vehicle) (for example, see Patent Literature 1 and Patent Literature 2). A conductive plate described in Patent Literature 1 is provided to prevent leakage of a magnetic field to the outside. In this way, a magnetic flux generated from the power transmission coil device is prevented from passing through an iron plate as a floor of a vehicle. A metal frame described in Patent Literature 2 is provided to prevent the power reception coil device from being damaged by colliding with another object.